Which option also is required on the tunnel interface before it is operational?

An engineer is configuring a GRE tunnel interface in the default mode. The engineer has assigned an IPv4 address on the tunnel and sourced the tunnel from an Ethernet interface .

Which option also is required on the tunnel interface before it is operational?
A . (config-if)#tunnel destination <ip address>
B . (config-if)#keepalive <seconds retries>
C . (config-if)#ip mtu <value>
D . (config-if)#ip tcp adjust-mss <value>

View Answer

Answer: A

Explanation:

A GRE interface definition includes:

+ An IPv4 address on the tunnel

+ A tunnel source

+ A tunnel destination

Below is an example of how to configure a basic GRE tunnel:

interface Tunnel 0 ip address 10.10.10.1 255.255.255.0 tunnel source fa0/0 tunnel destination 172.16.0.2

In this case the “IPv4 address on the tunnel” is 10.10.10.1/24 and “sourced the tunnel from

an Ethernet interface” is the command “tunnel source fa0/0”. Therefore it only needs a tunnel destination, which is 172.16.0.2.

Note: A multiple GRE (mGRE) interface does not require a tunnel destination address.